Is There A Performance Advantage To Internal Femoral Rotation During A Broad Jump?

Abstract

Internal femoral rotation, resulting in greater knee valgus angle, occurs in some individuals during broad jumps. Fitness professionals consistently train athletes away from this movement prior to jumping for fear of injury. However, given the knowledge regarding optimal cross-bridge potential and stimulation of the stretch shortening cycle, it is theorized that internal femoral rotation during jumping may recruit additional hip muscle cross-bridges and utilize the stretch shortening cycle resulting in better performance. PURPOSE:To investigate the effect of knee valgus angle on broad jump performance. METHODS:A sample of 18 males aged 20-29, recreationally trained jumpers performed a brief warm-up followed by 3 control jumps (C) and 3 internally rotated jumps (IR). During the IR trial, participants were given a ball to hold between their knees. The ball was then removed. The participants were then instructed to focus on keeping their knees closer together as if squeezing the ball at the bottom of the countermovement while attempting to jump as far as possible. During the C trial, participants were instructed to jump as far as possible. Fourteen individual retro-reflective markers and rigid body markers were applied to track kinematic data. Jump distance was measured from the starting line to the nearest 1 cm increment of participant’s heels. False step trials were not used. RESULTS:Knee valgus angle was greater (p<0.05) during the IR trials for both the right (C= 4.9±4.0o, IR= 6.4±4.0o) and left (C= 5.7±4.3o, IR= 8.9±5.1o) leg. Furthermore, C jump distance (2.27±0.25m) was significantly greater (p<0.05) than IR jump distance (2.17±0.25m). CONCLUSIONS:This data suggests that avoiding valgus knee collapse during broad jumping may be beneficial for injury prevention and performance; therefore fitness professionals should teach clients to avoid hip internal rotation during jumping.